Magnetic switch



May 6, 1941.

MAGNETIC SWITCH Filed Aug. 11, 1938 2 Sheets-Sheet l May 6, 1941.

c. v. HILDEBREcH-r 2,240,847

MAGNETIC SWITCH Filed Aug. 11, 193s 2 sheds-sheet 2 #di L/zd Y. fm/rdm Patented May 6, 1941 UNITED i STATES PATENT OFFICE MAGNETIC SWITCH Charles V. Hildebrecht, Chicago, Ill., assigner to Milwaukee Ga's Specialty Company, Milwaukee, Wis., a corporation of Wisconsin Application August 11, 193s, .serial No, 224,248

(ci. 20o-a7) Claims.

issued May 15, 1934.

According tothe present invention, I provide a switch in which the switch contacts operate in a vacuum tube or in a tube lled with an inert which increases the emciency and currentcarrying capacity of the switch, and it removes from the contact leads the weight of the arma-A ture and its yielding supportand the stresses which otherwise would be imposed on at least one of the contact leads. Where the movable contact means is carried on the resilient support described in Oscar J. Leins Patent No. 1,958,482,

or other gas. The tube is adapted to be mounted in the desired position and connected into the circuit between the devices controlled, by the switch and the source of current therefor. The switch contacts are disposed within the tube and one of these contacts is carried by yielding means and normally separated or spaced from the other contact thereby. It is to be understood, of course, that the switch may be of the normally closed type within the scope of the present invention,

,in which case the contact carried by the yielding means will be normally held in contact with the other contact and will be separated therefrom in the manner hereinafter described in connection with the closing of the yleldingly mounted contact into contact with the other contact or contact means.

'Ihe switch is also provided with an armature which is adapted to be attracted by a relatively small permanent magnet coming into proximity thereto for closing the movable contact carried by the yielding means into contact with the other contact or for opening the movable contact from .ontact with the other contact with a snap action.

Also, because of the tension in the yielding means carrying the movable contact, the removal of the magnet will cause a snap movement of the movable contact to the other position. 'Ihis snap action'in both directions is highly desirable, since it will materially decrease any arcing which might otherwise occur.

An important aspect of the present invention consists in supporting the armature yieldingly within the tube and at the same time independentl'y of the contact leads and on the yielding means carrying the movable contact or independently thereof. This removes the armature and its yielding support from the electric circuit,

for the armature the weight ofthe movable con- .tact and any stresses which `otherwise might be imposed thereby are also removed from the contact leads.

In the illustrated embodiment of the invention the means for causing movement of the magnet for opening and closing the switch is provided by a thermally sensitive bimetallic element which carries the permanent magnet. 'I'he movement of the permanent magnet in response totemperature changes or the like causes the magnet to assume a position whereby the armature is attracted, for example, for closing the contacts and thus completing the circuit to the device controlled by the-switch. As this controlled device functions to compensate for movement of the magnet, the magnet will tend to return toits normal position and, when it reaches a position at which' the magnetic attraction is less than the tension of the yielding means within the tube, the

/ circuit will be opened by the snap action of the movable contact away from the other contact.

The invention 'is of particular use in connection with room thermostats, oven and furnace controls, and temperature limiting controls, and may be employed in a two-wire control system, as shown, or in a system employing more than one circuit control, in which case additional armatures and contacts are provided.

Other features and-advantages of the invention will appear from the following detailed description taken in connection with the accompanying drawings, in which: Figure 1 is a more or less diagrammatic sectional view showlng a magnetic switch embodying the present invention;

Figure 2 is a section taken on the'llne 2-2 of Figure 1;

Figure 3 is a sectional view showing another form of switch embodying the present invention; Figure 4 is a section taken on the line 4 4 of Fig. 3;

Figure 5 is a view similar to Figure l,A showing another form of switch embodying the present invention; l v

Figure 6 is a section taken on the line 6 6 of Fig. 5;

Figure 7 is a view similar to Figure 1, showing another embodiment of the invention;

Figure 8 is a section taken on the line 8 8 of Fig. 7;

Figure 9 is a sectional view showing another embodiment of the invention; and

Figure 10 is a section taken on the line IIi-IIl of Figure 9.

Referring now in detail to the drawings, in all embodiments of the invention the switch includes a cylindrical casing, envelope, or closed tube indicated at lli in Figures 1 and 2, which tube is evacuated or filled with an inert gas. The tube II) is formed of glass quartz, or other suitable non-magnetic and preferably transparent material, although the transparent characteristic need not be present. Y

In Figures 1 and 2 the tube Iliis provided with a pair of lead-in wires II and I2 which are secured and sealed in the end portion I3 of the tube. One contact lead I4 extends from the lead-in wire II and at its free end carries a contact I5. The contact lead I4 may be in the form of an integral extension of the lead-in wire II, or it may be formed separately and connected to the lead-in wire. It is preferably relatively rigid, to support the contact I5 in fixed position, but it may be of yielding character within the scope of the present invention.

The other contact I6 constitutes the movabler contact of the switch. It is yieldingly lsupported in proximity to the contact I5 by yielding means in the form of a leaf spring member I1 suitably secured to thellead-in wire I2 at I8. The contact IB is disposed on the end of the spring member I1 and is electrically connected with the lead-in wire I2 through the spring member I1, the contact I5 being electrically connected with the lead-in wire II through the contact lead I4. Where the lead-in wires II and l2 are of suitable character the contact lead I4 and spring member Il need not be in the form of separate members but may be formed by inward extensions of the lead-in wires. In this embodiment of the invention the contact I5 is normally resiiiently spaced from the contact I5 and is adapted to be engaged with the contact I5 for closing the circuit controlled by the-switch.

lThe switch is also provided with an armature 20 secured to the free laterally turned end of a yielding support shown in the form of a leaf spring 2|. The opposite end of the spring 2I is anchored at 22 in the end portion I3 of the switch tube. 'I'he spring 2I has an insulating member 2l secured thereto at 24 and adapted by engagement with the yielding contact lead Il to press the contact Il into engagement with the contact I5 when the amature 20 is attracted to the left as viewed in Figure 1. The armature 20 is formed of magnetic material such as soft iron or the like.

The yielding support 2| may be of spiral or other suitable form instead of the form shown, and the form of the other elements of the switch may be varied within the scope of the present r invention.

Disposed externally of the casing It isa thermally sensitive member 25 which preferably comprises a. pair of metal strips suitably secured together, the strips having different coemcients of expansion. At one end the thermally sensitive member 26 is secured to a member 21 and xedly held in position thereby. A permanent magnet 28, shown in the form of a relatively small horse shoe magnet, is mounted at 29 upon the other end of the thermally sensitive member 26 and has its poles presented toward and generally in alignment with the armature 20.

Upon variations in temperature the thermally sensitive member 26 is adapted to warp to the position shown in dotted lines in Figure 1.and when the magnet 2B is brought sufliciently close to the tube I0 the attraction of the armature 20 by the magnet 28 is sufficient to pull the armature toward the magnet, as shown in dotted lines in Figure 1. The movement of the armature 2li to the dotted line position flexes the armature-carrying spring 2i to the left and, in thus flexing, the spring 2| acts through the insulating member 23 to flex the contact spring I'I to the left to engage the contact I6 carried thereby with the contact I5. The foregoing movement of the armature 20 and contact I6 to the left results in tensioning the springs Il and 2i.

Engagement of the contact IS with the contact I5 closes the electric circuit which is connected to the lead-in wires of the tube and the closing of this circuit actuates a suitable control device for varying the temperature. Upon compensating for the condition which caused the member 26 to warp to its dotted line position (Figure l), for example, upon bringing the temperature to the temperature which the apparatus is set to maintain, the member 26 will tend to draw away from the tube I Ii, and at the point at which the magnetic attraction between the magnet 2B and the armature 20 is not as great as the tension of the springs I1 and 2| the contact I6 will snap away from the contact I5 and the circuit will be broken. A snap action is thus secured in each direction, which is highly beneficial. The cycle of operation may be continued indefinitely.

From the foregoing description it will be apparent that the armature 20 is supported yieldingly within the tube I0 and at the same time independently of the contact leads and independently of the yielding means carrying the movable contact I6. This removes the armature 2li and its yielding support 2I from the electric circuit, which increases the current carrying capacity and efliciency of the switch and the contact leads and lead-in wires are-also relieved of the weight of the armature and its yielding support and of the stresses which otherwise would be imposed on at least one of the contact leads.

I contemplate, within the scope of the present invention, providing the armature carrying spring ZI with means not only foractuating the contact I8 into engagement with the contact I 5 when the spring 2I is moved by the magnet 2B but with means for snapping the contact I6 out of contact with the contact I5 by the tension in the armature spring at the point where the magnetic attraction is not as great as the tension in the spring 2|. With this latter provision the spring-like or resilient character of the contact lead I'I may be omitted.

In the embodiment illustrated in Figures 3 and 4 the switch tube is indicated at IIIa and the leadin wires at IIa and I2a, these wires being se- `cured and sealed in the end portion I 3a oi' the tube as before. In this case the inner ends oi' the lead-in wires or suitable contact leads eirtending therefrom carry fixed contacts 32 and 33 in spaced relation within the tube. 'I'he annature spring 2Ia, which is anchored at 22a in the end portion I3a of the switch tube. as before, carries at its opposite end not only the amature 20a but an insulating block 34 to which a bridging contact 35 ls secured at 36.

`The thermally sensitive member 26a is disposed externally of the tube Illa., as before, and preferably comprises a pair of metal strips suitably secured together, the strips having different coelcients of expansion. This member 26a may be of the form shown in Figure 1 or it may be of spiral or any other form, anchored at its opposite end or otherwise suitably held in position. The permanent magnet 28a is mounted at 29a upon the thermally sensitive member 26a and has its poles presented toward and generally in alignment with the amature 20a, as in the preceding embodiment of the invention.

Upon variations in temperature the thermally responsive magnetic means moves into position for attracting the armature 20a. The movement of the armature 20a into attracted position, as indicated by the arrow 38 in Figure 4, moves the bridging contact 35 into engagement with the contacts 32 and 33, which closes the electric circuit connected to the lead-in Wires of the tube. As before, upon compensating for the condition which caused the member 26a to move to position to attract the armature 20a, the member 26a will tend to draw away from the tube lia and at the point at which the magnetic attraction between the magnet 26a and the armature 20a is not as great as the tension of the spring 2|a, the bridging contact 35 will vsnap away from the contacts 32 and 33 and the circuit will be broken In the embodiment shown in Figures and 6,

`the switch tube is indicated `at Ib and .the leadin wires at IIb and |2b. In this form of the invention the lower end of the tube |017 has a depending cup or pocket 42 in which is retained a small pool or body of mercury or other fluid electrical conductor 43. or a contact lead extending therefrom as indicated at 44 engages, at its inner end, the mercury 43 and preferably terminates below the surface thereof. The lead-in wire I2b or a contact lead extending therefrom as indicated at 44' is preferably of flexible and resilient character and is bent out and down and terminates in a contact end 45 normally out of contact with the mercury 43. The contact lead portion-44 of this embodiment of the invention and the similar portions of the other embodiments may be formed or provided with means to increase the resiliency thereof if and as desired.

The armature 20h of magnetic material is carried by a downward extension 46 of a sensitive spiral spring 41 which in turn is carried by a supporting member 46 anchored at 49 in the end portion l3b of the'tube 10b. 'Ihe armature 20h in this case is generally U-shaped and is secured at 50 to the spring arm 46 with the legs of the armature straddling the contact lead 44'. An insulating member 5l is secured to the base of the U-shaped armature between the legs thereof, and, when the armature is attracted by the magnet 28h, cooperates with the contact lead 44', forcing the same to the left (Figure 5) and thereby causes the contact end 45to contact and enter the mercury 43, thereby closing the circuit through the switch'. When the magnet 28h is moved away from the tube. Illb, for example by the blmetallic element 26h anchored at 52, the pull on the armature is released and the resiliency of the lead 44' and spring 41 snaps the contact end 45 out of engagement with the mercury,

thereby breaking the circuit and the armature 26h moves to the right as viewed-in Figure 5.

The lead-in Wire I'Ib If desired, the armature of .this or any of the other embodiments of the invention may be vmerely supported yieldingly for movement in one lead-in wires Hc and I2c or by contact leadsl4c and I1c extending therefrom as shown. The armature 20c, which is carried by the spring arm 2 lc above .the insulating member 23c is generally U-shaped, with its legs straddling the contact lead I1c for cooperation with the magnet 26e. The switch tube is indicated at Ic. Also, in this embodiment, the thermally sensitive member 26e is in the form of a bimetallic spiral at 56, and a range adjustment arm and range adjustment screw are provided at 51 and 58, respectively, for adjusting the device so that the magnet 28e will be moved into Iand out of vcooperation with the armature 20c at any desired temperatures. A pointer 59 on the arm 53 cooperates with a scale 60 on a fixedly positioned member 6I for indicating the temperature for which the device is adjusted.

The embodiment shown in Figures 9 and 10 is similar to the embodiment shown in Figures 3 and 4,except that in this case the bridging contact 35d is normally held yielding and resiliently by the spring Zld in contact with the contacts 32d and 33d carried by the lead-in Wires lid and I2d or extensions thereof. The switch, the tube oi which is indicated at llld, is thus normally closed and is opened by bringing the magnet 28d into position to attract the armature 26d and thereby move the bridging contact 35d out of engagement with the contacts 32d and 33d. In this case the bimetallic thermally sensitive member 65 is shown in helical form, encircling the tube I0d and anchored at 66 d with the magnet 26d secured to the opposite ndl thereof at 61. I n operation, variations in temperature will cause thehelically coiled thermally sensitive member to expand or contract, causing rotary motion of the magnet 28d about the tube 10d to move the magnet into and out of position for attracting the armature 20d and opening the switch. This embodiment may be normally open instead of normally closed, and the magnet arranged to closethe same in operation, and the other embodiments of the invention may be normally closed with the magnet arranged to open the same in. operation. f

I do not intend to be limited to the particular details shown or described, since various modications other than those .herein illustrated and described may be' made without `departing from the spirit and scope of the invention. For example, in their .broader aspects the appended claims are intended to cover not only the various em-` fork member is carried bythe flexible and resil ient arm carrying the armature and adapted to be moved into engagement with the pools of mercury by the thermally responsive magnetic means to close the electric circuit.

I claim:

1. In combination, a non-magnetic sealed switch casing, terminal -leads extending into said casing, relatively fixed contact means within said casing, contact means movable into and out of engagement with said relatively fixed contact means to open and close an electric circuit, an armature disposed within said casing and operable to actuate said movable contact means, and means resiliently supporting said armature within said casing wholly independently of all of the terminal leads extending into said casing, said armature and the supporting means therefor being wholly removed from all electric circuit connections through said casing.

2. In combination, a non-magnetic sealed switch casing, terminal leads extending into said casing, relatively fixed con-tact means within said casing, contact means movable into and out of engagement with said relatively fixed contact means Vto open and close an electric circuit, an armature disposed within said casing and operable to actuate said movable contact, and means resiliently supporting said armature within said casing independently of all of the terminal leads extending into said casing, said armature and the supporting means therefor being wholly removed from all electric circuit connections through said casing.

3. In combination, va non-magnetic sealed switch casing, terminal leads extending into said casing, relatively xed contact means within said casing, contact means movable into and out of engagement with said relatively fixed contact means to open and close an electric circuit, an armature disposed within said casing and operable to actuate said movable contact, a resilient arm supported within said casing wholly independently of al1 of the terminal leads extending into said casing, said armature and the supporting means therefor being Wholly removed from all electric circuit connections through said casing, said resilient arm supporting said armature and said movable contact means, and means insulating said armature from said movable contact means.

4. In combination, a non-magnetic sealed switch casing, terminal leads extending into said casing, relatively iixed contact means Within said casing, contact means movable into and out of engagement with said relatively fixed contact means to open and close an electric circuit, an armature disposed within said casing and operable to actuate said movable contact means, a resilient'arm supported within said casing wholly independently of all of the terminal leads extending into vsaid casing, said armature and the supporting means therefor being wholly removed from all electric circuit connections through said casing, said resilient arm supporting said armature and said movable contact means, and means insulating said armature from said movable contact.

5. In combination, a non-magnetic sealed switch casing, terminal leads therefor, relatively iixed contact means within said casing, a contact member within said casing and adapted for movement into position out of contact with said relatively iixed contact means and into position in contact with said relatively x'ed contact means to open and close an electric circuit, an armature member disposed within said casing and operable to move said contact member into one of said positions, and means resiliently supporting at least one of said last two members, said resilient supporting means being tensioned upon movement ci' said armature lin moving said movable contact member to one of its positions and operable to snap the movable contact member to the other position, said armature and said resil- `disposed Within said casing and operable to move said movable contact member into one of said positions, means resiliently supporting both of said last two members, said resilient supporting means being .tensioned upon attraction of the armature in moving the movable contact member to one of its positions and operable to snap the movable contact member .to the other position,

said armature and said resilient supporting means being wholly removed from all electric circuit connections through said casing and having support independent of said terminal leads.

7. An electric switch unit including a sealed casing having normally disengaged switch contact means therein for opening and closing an electric circuit, terminal leads for said switch unit, and an armature resiliently supported within said casing and wholly removed from all elecytric circuit connections through said casing, movement of said thermally sensitive element due to temperature changes causing said magnet to move adjacent said armature for attratcing same and thereby closing said contact means.

8. An electric switch unit including a sealed casing having normally disengaged switch contacts therein tor opening and closing an electric circuit, terminal leads for said switch unit, an armature wi-thin said casing, and a resilient arm supporting said armature and one of said contacts independently of the terminal leads and wholly removed from all electric circuit connections through said casing.

9. In combination, a non-magnetic sealed switch casing, terminal leads extending into the casing and having contact means within said casing, a resilient arm supported within the casing and wholly independent of all electric circuit connections through said casing, an armature supported on said resilient arm, and a bridging contact supported on said resilient arm in insulated relation relative said armature and said arm-and adapted to -be actuated into contact with said contact lmeans when said armatureris attracted and snapping out of contact with said contact means when the armature is released.

10. In combination, a non-magnetic sealed switch casing, a terminal lead extending into the casing and having a relatively fixed contact thereon, a second lead having a resilient extension extending into the casing and having a movable contact Ithereon spaced from said fixed contact, resilient means supported within the casing wholly independently oi' all electric circuit connections through said casing, and an armature resiliently supported on said resilient means, and

adapted to be attracted to cause engagement o1' said contacts.

11. In combination, a non-magnetic sealed switch casing, a terminal `lead extending into the casing and having a relatively fixed contact thereon, a second lead having a resilient extension extending into the casing and having a movable contact thereon spaced from said fixed contact, resilient means supported within the casing wholly independently of all electric circuit connections through said casing, and an armature resiliently supported on said resilient means, and adapted to be attracted to cause engagement of said contacts, said resilient armature supporting means comprising a Spring member having an insulating member thereon for engaging the resilient extension of the terminal lead for the movable contact.

12. In combination, a non-magnetic sealed switch casing, a terminal lead extending into the casing and having a relatively xed contact thereon, a second lead having a resilient extension extending into the casing and having a movable contact thereon spaced from said iixed contact, resilient means supported within the casing wholly independently of all electric circuit connections through said casing, and an armature resiliently supported on said resilientmeans, said resilient armature supporting means comprising a spring member having an insulating member thereon for engaging the resilient extension of vthe terminal lead for the movable contact, said armature being of generally U-shape with its legs straddling the resilient extension of the terminal lead for the movable contact member.

13. In combination, a non-magnetic sealed switch casing, a body of electrical conducting uid therein, a. terminal lead having an extension extending into the switch casing and into contact with said iluid, a second terminal lead having a resilient extension extending into the switch casing and provided with a contact normally out of contact with said uid, an armature resiliently supported within said casing wholly independently of all electric circuit connections through said casing, and adapted to be attracted to move the contact on the resilient extension of said second terminal lead into contact with said electrical conducting fluid.

14. An electric switch comprising a sealed tube, current conducting means within said tube, an electrode disposed within said tube and having its inn-er end movable to a rst position in contact with said current conducting means and to a second position out of cont-act with said current conducting means, an armature disposed within said tube and operable to actuate the movable inner end of said electrode from one of said positions to the other position, and means wholly removed from all electric circuit connections through said tube for supporting the armature within said tube.

15. An electric switch comprising a sealed tube, current conducting means within said tube, an electrode disposed within said tube and having its inner end movable to a rst position in contact with said current conducting means and to a second position out of contact with said current conducting means, an armature disposed within said tube and operable to actuate the movable inner end of said electrode from one of said positions to the other position, and means wholly removed from all electric circuit connections through said tube for supporting the armature within said tube, said last. means resiliently maintaining said armature in and returning same to one of said positions.

CHARLES V. HILDEBRECHT. 

